Adjustable gun choke and method of constructing the same



E h H W F E Filed March 24. 1931 2 Sheets-Sheet FULL Dec. 27, 1932. E.F. WHITE 1,892,522

ADJUSTABLE GUN CHOKE AND METHOD OF CONSTRUCTING THE SAME Filed March 24.1931 2 Sheets-Sheet 2 l 69 q J V A Patented Dec. 27, 1932 EZEKIEL F.WHITE, OF WEST HARTFORD, CONNECTICUT ADJUSTABLE GUN CHOKE AND METHOD OFCONSTRUCTING THE SAME Application filed March 24, 1931.

This invention relates to adjustable choke devices for the end of a gunbarrel and methods of constructing the same and consists in improvementsdesigned to render such devices more efficient than heretofore, as wellas convenient and simple in the method of handling.

The invention will be best understood by reference to the followingdescription when taken in connection with the accompanying illustrationof one specific embodiment thereof, while its scope will be moreparticularly pointed out in the appended claims.

In the drawings:

Fig. 1 is a side elevation of the end of a gun barrel equipped with achoke device embodying one form of the invention;

Fig. 2 is a similar view on an enlarged scale and partly in section toshow the internal construction;

Fig. 3 is an end elevation of the choke device shown in Fig. 2;

Fig. 4 is a cross-sectional elevation on the line 44 in Fig. 2; and

Figs. 5, 6 and 7 are views each embodying an end elevation and alongitudinal section, more or less diagrammatic, to illustrate theprinciple utilized in the construction of the choke.

Referring to the drawings and to the em bodiment of the inventiontherein shown for illustrative purposes, the gun barrel 11 has anexternally threaded end on which there is firmly screwed to a shoulderedseat the hollow cylindrical shell 13 which projects forwardly from theend of the barrel and the interior of which provides an extension of thegun bore. The forward end of the shell 13 is separated into a number ofsegments 15 (herein six in number) by means of slots 17 which extendparallel to the axis of the shell from the forward end thereof to apoint spaced from the end of the gun barrel, terminating each in acircular enlargement 19, the advantages of which, both from its circularshape and enlarged character, are hereinafter set forth.

lVhile in the described embodiment the choke shell 13 is in the form ofa separate attachment applied by threaded engagement to Serial No.524,811.

the end of the gun barrel, it may, if desired, be formed by the end ofthe gun barrel itself, or, as a separate piece, may be applied andfastened to the gun barrel by other methods than by threading the samethereon.

A choke adjusting sleeve 21 fits over the projecting end of the chokeshell and is in threaded engagement with the rearward, unslotted,externally threaded portion of the shell. The forward or outer end ofthe adjusting sleeve has a contracted, internally beveled end 23 tooverlie and engag with a correspondingly beveled end of the choke shell.By turning the sleeve on the choke shell, the sleeve may be screwedrearwardly (35 on the shell, causing the segments to spring inwardlythrough the action of the beveled end 23 of the sleeve. Through thismeans any desired degree of choke may be secured, the full chokeposition being reached when the ends of the segments contact each withits adjoining one, the width of the slots 17 being sufiiclent to g vethe desired range of choke.

The exterior rear end of the sleeve 21 is provided with graduations 25(herein six in number) suitably designated and cooperatively positionedwith relation to some fixed reference point on the shell, such as thesight 27 so that the rotative position of the adj usting sleeve on theshell may at all times be indicated to the user of the gun and thelatter may be made aware of the adjustment of the choke, whether fullchoke or some fractional part thereof.

Cooperating with the graduated indicator is a stop or posit oning deviceadapted to hold the adjusting sleeve in its rotative movement at anypoint to correspond to one of the graduations on the sleeve. For thispurpose the sleeve 21 is provided with an external, circumferentialgroove 29 in which there is seated an encircling split spring-ring 31,one end 33 of which is bent inwardly and, protruding through an openingin the sleeve at the bottom of the groove 29, has a beveled tip which isadapted to enter any one of the slots 17, as indicated in Figs. 2 and 4.

When the sleeve is turned on the shell, the beveled, in-turned end 33 ofthe resilient ring is for ed out of the slot 17 and rides over the wallsof the shell, snapping into and out of each successive slot unt l thesleeve is brought to rest at the desired point of choke, when thebeveled end 33 snaps 'into the corresponding underlying slot and holdsthe sleeve fixed in its assigned position, serving as a resilient clickstop or positioning and locating device.

Preferably the pitch of the threads between the sleeve and the chokeshell is such that one complete rotation of the sleeve provides thedesired range of adjustment, from the full open to the full closed chokepositions.

The curved walls of the circular slot-terminals 19 at the ends of theslots 17 min mize any tendency of the walls of the sleeve to rupture inline with the slots under the explosive action of the gun; and theenlarged character of the slot terminals 19 is particularly desirable tolocalize the bend of the choke segments at the said ends thereof. Theenlargements at the ends 19 of the slots results in a weakening of theresistance to bending of the segments thereat, so that upon choking ofthe gun most of the bend occurs at the roots of the segments with theresult that a rectilinear taper is approximated, whereas the segments ofchokes not weaker at their roots than in their length tend to bendprogressively from their roots to their tips giving a curvelinear taperresulting in a less uniform shot pattern.

In adjustable choke attachments as heretofore constructed, the split orsegmental choke shell has been provided with a bore which is trulycylindrical and constitutes a cylindrical extension of the bore of thegun barrel when the shell is expanded so that the segments are in linewith the barrel bore. lVhen a shell so constructed, however, iscontracted by springing the ends of the segments together to the fullchoke position, the inner periphery of the choke shell becomes more orless distorted out of a truly cone-shaped surface.

The effect of this will be apparent from Figs. 1 and 2, where, forsimplic'ty, there is shown a cylindrical choke device 35 split into foursegments 37 by means of the slots 39 of exaggerated width. The chokedevice 35 may be either the end of the barrel itself or a separate shellattachment. In its normal or open position, as shown in Fig. 5, the boreof the shell is a true cylinder and each cross section thereof iscircular in form and composed of four concentric arcs 41. If the endsofthese segments are-sprung together, however, as shown in Fig. 6, anycross-section of the slotted portion of the shell is no longer circularin form but is composed of the four arcs 41 which are nownon-concentric. The inner surface of the bore therefore does not conformto the surface of a cone but departs materially therefrom.

The concentrating action of the choke on the discharge from the gundepends upon a ricochet action which is most pronounced under conditionsof full choke. To secure a. uniform distribution of the shot when thechoke is used this action should be as nearly uniform as possible indifferent circumferential portions of the bore. In the case of a chokeshell constructed on the principle represented in Figs. 5 and 6, I havefound that the pattern produced tends to be fnetficient, irregular andnon-uniform, apparently due to the departure of the bore of the chokeshell from a conical form.

In constructing the choke shell disclosed in Figs. 1 to 5 inclusive,this condition is avoided so that, at the target or object shot at, agreatly improved and more efficient pattern is provided for by soforming the bore of the shell that when contracted to a full chokeposition the bore has a truly conical shape, the inner periphery of eachcross section thereof being circular in form. Such a condition forcomparison is represented in Fig. 7.

This result is secured by first forming the choke shell with acylindrical bore. The shell is then split to form the desired number ofseparated segments. The adjusting sleeve 21 is then screwed on to thechoke shell so that the maximum contraction is had and the ends of thesegments are sprung into contact with each other. In this condition ofmaximum contraction, suitably tapered reamers. having the correct amountof taper to produce the desired cone for the full choke position, areinserted and the interior reamed out so that a true cone-shaped bore isproduced throughout, changing the shell from a condition which may berepresented in Fig. 6 to that which may be represented in Fig. 7.

With the choke shell constructed under this plan, when the segments aresprung together into the full choke position, the coke assumes a truecone-shape, providing a highly eflicient pattern for longer ranges, witha much more uniform distribution of the shot bothat full choke andpartial choke positions.

As above pointed out, the weakening of the roots of the segments 15, asby the enlargement of the terminal ends of the slots at 19., results ina more nearly rectilinear taper of the segments in all degrees ofcontraction, and this feature may be employed to produce an improvedshot pattern without reaming the contracted segments to a truly conicalbore. Similarly, the reaming to truly conical form at full chokeposition of a bore in which the segments are of uniform bending strengththroughout before reaming, provides an improved shot pattern at partialchoke position as well as at full choke position, even though the tipsof the segments are thinned more than the roots thereof with the resultthat at full open position they have a minute flare. However, byemploying segments both adaptseparated into ed to bend more freely attheir roots and defining a truly conical bore when fully contracted, anadditional improvement is effected in that the tips of the segments aremaintained somewhat thicker, because the reaming operation need notremove so much metal at the tips to straighten out the curve of bendingof the segments into a rectilinear wall, with the result that the tipshave little tendency to produce even a minute flare of the bore when thechoke is in full open condition, and a very nearly rectilinear taper ofthe choke is obtained at all positions from full choke to full open.

Vhile I have herein described and shown for the purpose of illustrationone specific embodiment of the invention, it is to be understood thatextensive deviations may be made therefrom, all without departing fromthe spirit thereof.

I claim:

1. The method of forming a choke shell for a gun barrel which consistsin constructing a metallic shell having a cylindrical bore, separatingone end of the shell into longitudinal segments, contracting theseparated end of the shell, and, while the latter is held contracted,shaping the bore into cone-shaped form.

2. An adjustable choke for gun barrels comprising a shell portion, themouth of which has rearwardly extending slots leaving an unslotted rearportion, said slots separating the end of the shell into spacedsegments, and an adjusting sleeve fitting over and bearing against theslotted end of the shell and having threaded engagement with theunslotted portion of the shell, whereby rotation of the sleeve serves tocontract the mouth of the shell, said shell when contracted to fullchoke position being shaped to present a true cone-shaped bore.

3. An adjustable choke for gun barrels comprising a shell portion havingits mouth detached segments, with means to contract the mouth of saidshell to provide a choked condition, said shell when fully contractedpresenting a bore of true cone-shaped form.

4. An adjustable choke for gun barrels comprising a choke shell, themouth of which is longitudinally slotted, a choke adjusting sleevefitting over said shell and having threaded engagement therewith andbearing against the slotted end of the shell, whereby rotation of thesleeve serves to contract the mouth of the shell, said sleeve having anexternal circumferential groove, and a resilient ring seated in thegroove having an in-turned end protruding through an opening in thesleeve, whereby the protruding end of the ring is adapted to enter oneof the longitudinal slots in said shell and serve as a resilientpositioning device for the sleeve.

5. An adjustable choke for gun barrels comprising a slotted choke shellportion, a choke adjusting sleeve rotatably mounted on the shell, and aresilient positioning device carried by the sleeve and adapted to engagewith successive slots in the shell.

6. An adjustable choke for gun barrels comprising an adjustable chokeshell portion, an adjusting sleeve mounted thereon, and a resilientpositioning and locating device carried by the sleeve.

7. An adjustable choke for gun barrelscomprising an adjustable chokeshell portion, a choke adjusting member cooperatively related thereto, apositioning and locating device to position said member in any one ofthe successive positions of adjustment, and an indicator to indicate thedegree of choke.

8. An adjustable choke for gun barrels comprising a slotted choke shellportion, a choke adjusting sleeve fitting over said shell portion andhaving threaded engagement with a part connected therewith, whereby saidsleeve may be turned step by step to a plurality of positions to securedifferent degrees of choke between full open and full choke positions,and a resilient positioning and locating device carried by the sleeve tolocate the sleeve in its step by step positions corresponding todifferent degrees of choke and prevent accidental displacementtherefrom.

9. An adjustable choke for gun barrels comprising a slotted choke shellportion, a choke adjusting sleeve fitting over said shell portion andhaving threaded engagement with a part connected therewith, whereby saidsleeve may be turn-ed step by step to a plurality of positions to secureditt'erent degrees of choke between full open and full choke positions,a resilient positioning and locating device carried by the sleeve tolocate the sleeve in its step by step positions corresponding todifferent degrees of choke and to prevent accidental displacementtherefrom, and a scale for indicating the rotative position of thesleeve whereby the degree of choke is readily ascertainable.

10. An adjustable choke for gun barrels having a choke shell, a chokeadjusting sleeve threadedly engaged with a part connected with saidshell and adapted to be turned to at least three predetermined positionsof adjustment thereon corresponding to three predetermined adjustmentsof the choke, said parts being proportioned so that at least three ofsaid predetermined positions lie within a single rotation of the sleeve,and indicating means associated with said choke adjusting sleeve andindicating said predetermined positions of adjustment thereof to providefor ready setting, checking or chang ing of the adjustment of the choke.

11. An adjustable choke according to claim 10 in which said indicatingmeans consists of an index and a scale arranged peripherally about thechoke to relatively widely separate the indicated predeterminedpositions of adjustment.

12. An adjustable choke for gun barrels, having a shell portionsegmentally divided at its mouth by longitudinally extending slots andmeans to contract the mouth of said shell portion to provide a chokedcondition and in which the terminal ends of the slots remote from themouth of the shell portion are enlarged to provide for more read bendingof the segments thereat than in t eir lengths.

13. Anadjustable choke for gun barrels having a shell portionsegmentally divided at its mouth by longitudinally extending slots andmeans to contract the mouth of said shell portion to provide a chokedcondition and in which the ends of the segments remote from the mouth ofthe shell-portioned are partially cut-away to render the segments morereadily bendable thereat than in their lengths.

14. The method of forming a choke shell for a gun comprising the stepsset forth in claim 1 and further consisting in weakening the segmentsadjacent their attached ends to cause them to bend more freely thereatbefore shaping the bore into cone-shaped form.

15. An adjustable choke according to claim 3, in which said segments aremore readily bendable at a point remote from the mouth of the choke thanin their intervening lengths. I

In testimony whereof, I have signed my name to this specification.

EZEKIEL F; WHITE.

